Printing plate and process and composition of matter for forming the same and process of printing



l alnlna la n.

nonnnr man, or new roan, n; r.

:1 l l lam THE aaarn AND PROCESS OF PRINTING.

lt o hrawtnyr.

To all whom it may concern c Be it known that l, ROBERT, dorm, a citinonof the United States, a resident of the city of New ltorlr, in thecounty of New t lfork and State of New York, have invented certain newand useful Improvements in Printing Plates and Processes of andCompositions of Matter for Forming the Sallie and Processes of Printing,of which the fol- 1 lowing is a specification.

My invention relates to printing plates and processes of andcompositions of matter for forming the same, and has, among otherobjects, the following: first, the production of a plate, andparticularly a lithographic plate, and more particularly of a plate suchas is used in photo-gelatine printing processes, and a process ofprinting by which plate printing press prints or repro- 2 ductions maybe made of a quality superior to any hitherto known in the art; second,the production of such a plate by which such prints or reproductions maybe produced at a speed greatly in excess of any tt hitherto possible inthe art; third, the derising of a process by which a printing plate maybe produced with less labor and expense and in a shorter time than hashitherto been possible in the art, and fourth, t0 the production of sucha plate which shall reduce the loss of time arising from press stops toa hitherto unattai'ned minimum; and to suchends my invention consists inthe improvement in printing plates and 35 processes of and compositionsof matter for forming the same and processes of printing hereinafterspecified.

ll/ly invention is capable of embodiment in many diderent forms ofplates and proct0 esses of producing such plates and of printing and bythe use of various compositions of matter in such production, and. whilell shall choose. for the purpose of illustrating my invention. the bestembodiment thereof t5 known to me, such embodiment is to be regardedonly astypical and my invention is not to be confined thereto.

The example chosen for illustration is designed for use on alitho-off'set printing 50 press. I may use as a base or backing for theplate. thin plates formed of metal, such as aluminum or zinc. ranging inthickness,

' for example, from .01 to .03 inches, or T may use other materials,such as a sheet of m pyroxylin, pyralin, or celluloid for suchapplication filed August 16, 1922. Serial No. aaaaar.

purpose. For the illustrative example, a metal plate is chosen, and thefirst step is to produce a grain or roughness on one side .of the platefor the purpose of increasing adherence of the gelatine coat theretowhich ll next put on it. For this purpose ll preferably effectv agraining equivalent to that of fine mudground glass, preferring that thegrain should be as fine as possible and merely presenting a roughsurface. It is to be understood that, as the said graining is simply forthe purpose of securing" the gelatine coating to the plate, it does notappear in the imprint from the plate and has no effect thereon as wouldbe the case with the grains which are produced on ph0to-lithographic oroffset plates for the purpose of breaking up the continuity of thephotographic image.

lhl'aving produced a grain upon my plate and thoroughly cleaned it ofgrit and metallic particles. as by a water spray, ll apply the coat ofgelatine thereto in any desired manner. as by whirling it with asolution of gelatine. A suitable solution for the purpose may consist ofwater, 32 ounces, and hard commercial gelatine, 2250 grains. thegelatine having first been soaked in cold water and then brought intosolution by raising the temperature to 120 F. The gelatinous solutionthus prepared is applied on the center of the grained plate, while thelatter is whirling at a rate, say of approximately 20 revolutions perminute, the temperature being preferably maintained at 120 F. underwhich conditions a proper thickness of coating is obtained. For mypurpose T prefer a coating measuring ap proximately .0008 to .0012inches in thickness. The plate is preferably permitted to whirl until itis dry. I

l'laving coated my plate and preferably dried it. I preferably subjectthe gelatine to a hardening agent, such as a bath consisting of alcohol.32 ounces, and formaldehyde, Wt 40 1 ounce. to which the plate issubjected for five minutes. The plateis then preferably again dried asin an enclosed Whirler for five minutes and subsequently washed in coldrunning water for five minutes, when Wt it is again preferably dried, asby whirling. The plate is now ready for the preferably next succeedingoperation, which is that of sensitizing. l find that plates thus coatedkeep indefinitely without deterioration and lltl tltli till ltd

I am, therefore, able to coat and harden them in quantities and have asupply alwa s on hand ready for sensitizing.

aving coated and preferably hardened my plate, I sensitize it by acomposition which, directly or indirectly, will render the gelatineselectively receptive to a printing medium such as ink. In the presentinstance, I sensitize the plate by immersion for two minutes in thefollowing solution:

Water 16 ounces Alcohol 32 Ammonium bichromate 450 grains Water 16ounces Alcohol 32 Ammonium bichromate 450 grains Erythrosine 90 Theplatebeing sensitized, is ready for exposure to light behind a negative (or apositive) and, as in the case of most chromatized colloids, I find itdesirable to effect exposurc as soon after sensitizing as possibleinasmuch as deterioration soon sets in.

If, after having performed the above described steps, I were to wash myplate in cold running water, I would find that those portions of theplate affected by light were harder than those portions unaffected bylight. I, however, do not wash the plate at this stage of itspreparation as would be done in other processes. While, in my plate, atthis stage there is a difference between the light-affected areas andthose unaffected by the light, yet that difference is insufficient toenable the plate to receive ink selectively.

Having effected the exposure under the negative, I next proceed with thesteps which give it its great selective ink receptivity, as well as itslater durability. For this purpose I desire to selectively lncrease thehardening action which has been started by the light in the chromatizedcolloid, and

to do so without equally hardening the colloid in its unaffected areas.7 I preferably use as a hardening agent a substance which, when theexcess of such agent is removed,

. leaves the light-affected portions of the film,

and preferably the entire surface of the film, in a dry state. I furtherprefer to use a hardening agent which also is not absorbed by the film.Therefore, having exposed my plate, and preferably without havin Iwashed out the unaltered bichromate, I pre erably subject it immediatelyto a hal'denaffected portions.

Preferably after again washing the plate, I further harden the'hardenedrtions, as by placing the plate in a bath ofgure grain alcohol of highproof for two minutes. I find that although the unhardened portions arewater-soaked, they are not materially affected by this treatment, sincethe ammonium salt has been washed out. After this second bath of alcoholI again dry the plate, preferably by whirling, whereupon it is ready forthe last step in its preparationnamely, that of heating. This iseffected by placing the plate in say, for three minutes, an oven inwhich, for instance, a temperature of approximately 400 F. ismaintained. I-find that the effect of. the heating is twofold; first,the heat completes whatever chemical action has been started between thegelatine and bichromate thro h light exposure and the alcohol, andiereby materially hardens the light-affected areas and brings the plateto a point where there will be no further hardening effect even thoughthe plate be kept for months, since all the chemical action is complete,second, I find that heating as described has the effect of tougheningthe unaffected portions of the gelatine without materiallyreducing theirwater receptiveness, andat the same time increasing the degree ofadhesion between the gelatlne coating and the grained metal plate.

When the heating operation is complete, my plate is ready for the pressand, when fastened thereto, requires only moistening by water by suchmeans as are to be found on litho and offset presses to be a completedprinting plate.

When ink is applied to the wet surface of my plate in printing, I findthat, in effect, the ink is emulsified with the water and that a veryeffective printing results therefrom, the ink being so readily depositedon a print, or on a rubber blanket, as in offset printing, andredeposited therefrom upon the print or final support that, not only areprints of 1 high quality obtained, but they are produced at a muchgreater rate than has ever been done before.

My invention, while having some similaritics to other printingprocesses, has marked differences from and advantages over any of themwhichare known to me. I shall refer t it till

na-aaata particularly to photo-lithography, photoobtainable. by myinvention in a printing" press is markedly superior to those obtainablein that manner by any'other process known in the art, including thosejust ret'erred to, and the rate oil production is also much above thatpossible with such prior art. By my invention torty times as many printscan be made in a given time as with the pre vious photo-gelatineprocesses.

lln all photo-gelatine processes prior to mine, it has been necessary toterm a grain or reticulation in order to create a sutticient selectiveink receptivity to attain commercial results, but it is not necessary touse that expedient with my invention. lit has also been necessary, priorto my invention, to treat the photo-gelatine plate with a glycerinesolution in order to increase said selective ink receptivity. But myplate may be used smooth and efrainless, and l employ plain water inmoisteninp; it before inking, no glycerine or other agent for swellingthe gelatine being; required.

,lt is to be noted that in the present example a chromic acid salt isincorporated intmy film by first torming the gelatine film on the plateand then atterwards introducing the chromic acid salt by bathing, thefilm in a solution of such salt, and when a film is thus formed, it willnot become reticulated even though in the'previous dryinn it had beendried at a temperature which, it the salt had been incorporated with thegrelatine while the latter was in solution, would causereticulation,namely, a temperature approximating or above 130 h. l can,however, incorporate, the chromic acid salt in the film. byintroducing'it into a solution ot the ,qgelatine before the latter-isdepositeld upon the plate to form the film, by evaporation of itssolvent, and still obtain a film that is tree from reticulation, solong, as l[ do not heat it above 130 F.

While the portions of my colloid film which have not been afiected bylight are so receptive to water that they pertectly reject the inkwithout the aid of any other expedient than moistenina', the portions ofthe film whichhave been affected by light and which i are to receive theink to term the image still till possess some capacity tor absorbing;water,

and this capacity, in co-operation with the other qualities riven to thelight afif'ected portions by my said treatment, in some way repders suchportions unusually receptive to in it.

Because, therefore, of the tact that l print trom a wet ink-receptivesurface, while the phot -lithe and pheto-ofiset pla es are printed witha dry ink-receptive surface, l are able todeposit on the finished printa quantity of color impossible with such processes, and am thereforeenabled to print at much greater speeds than their plates permit.Furthermore, li eficct a noteworthy saving in press operation throughthe fact that, while the photo-litho and photo-offset plates have atendency to oxidize in the air and to lose their water receptivity,which makes necessary. at frequent intervals. a certain operation knownas summing, my plate cannot oxidize and requires no gulnniing, and in noway increases the number or duration of press stops. In other words,with my plate, it is not necessary to stop the press for grummingr, orfor any other operation to renew the selective receptivity of the plateto the ink which forms the print, as such selective receptivity dependsonly on the presence of the water, and this is automatically renewedafter each impression from the plate and without any stoppage of thepress.

Referring to the marked superiority in quality of prints andreproductions made accordin to rev invention as com ared with thequality of those made by the three printing processes above mentioned:ltn the photopelatine process, there is of necessity a grain orreticulation, finer or coarser, which is inherent to the formation ofthe plate.

from grain and reticulation may receive its image either trom acontinuous tone negative or from a negative made from a halttone screenor from one in which any manner of dot, grain, or particle is employed.

The plates used in the photo-lithe and photo-ofi'set processes must ofnecessity be made from negatives embodying a dot or grain. On the otherhand, my plate, printed on the same press, may be absolutely con tinuousin tone and tree from dot or grain, or, it desired, it may embody a dotor grain, which may be very much finer than any other grain hithertocapable of use in the said process. With my process, l have tound itpracticable to use dots which were sin times as many to the inch as themost that have been. used in photo-lithe and photo-otlset processes, sotar as l[ am aware. For instance, in practice it has been found that adot averaging to the inch produces the best results in photo-litho andphoto-offset printing, and, while dots as fine as to the inch have beenemployed, they have not been deemed commercially practicable or comeinto general use. With my plate, however, under commercial conditions Ihave found it practicable to use a dot as line as 400 to the inch and agrain as fine as 1200 to the inch.

liltt The degree of fineness of the dot or grain which it is possible touse with my plate is limited only by the ability to .produce a screenbearing them. \Vhile, in theory, a continuous tone image such as myplate alone is capable of rendering is theoretically desirable, yet, dueto inequalties of paper surface and other commercial factors, 1 find itusually preferable to employ a very fine screen or grain, but it ischaracteristic of my plate that its wearing qualities and its ability togive continuously perfect reproductions are not influenced, one way orthe other, by the fineness of the dot or grain used. I

A suitable way in which to form dots upon one of my plates is to formthem on the negative, fromwhich the plate is to be printed, in a camerain the manner in which dots are formed in the well-known half-toneprocess, where the dots are formed by focusing a screen, either regularor irregular, between the lens and the sensitive plate.

A suitable way in which to form grain or reticulation on one of myplates is by printing from a negative made as described in my UnitedStates Patent No. 1,374,853, April 12 1921.

in all reproductive processes, other than mine, wherein a screen, eitherdot or grain, is used whether in photo -engraving for relief printing orphoto-offset or lithography for photographic printing, a number of stepsare involved in the process which forbid the use of a dot or grain asfine as that which I can employ. These steps are those intermediatebetween the exposure of the colloidal bichromated surface to the lightand the actual inking of the plate on the press. They involve, forinstance, developing away unexposed portions with water and cotton wool,rubbing up with ink or acid resist, etching, re -etching, etc. No matterhow careful the manipulations, these operations would change thecharacter or formation of the dot or grain, if one were present as fineas I am able to use, so that much of the result accomplished by exposureto light would be lost when the printing plate was finally inked.

In my process, there is no change in the surface of the plate betweenits condition when exposed to light and its condition when finally inkedto make an impression, and there are no manipulations that can possiblychange the size, shape, or character of the dots imprinted by the light.I believe, in fact, that'I am the first to produce a printing platecapable of taking ink on a printing press on which the impression is tobe formed in which the dots or grains produced by light action areunaltered by manipulations of any kind; such as, reticulation,development, etc., previously mentioned. I further believe that I am thefirst to prepare a printing plate wherein the ink image correspondsexactly to the action of the light in the exposure.

A printin plate made accordin to my invention wil receive inkselectively as to its light affection from a roller passed over itssurface at a much higher speed than will any other photo-gelatine plateor plate having a colloid film with which I am familiar. With my plate,the ink-applying roller may be passed over its surface at a speedgreater than six inches per second.

In my process, as the portions of the plate which are to print the imageare moistened with water before ink is applied to them, and are at alltimes both water-receptive and charged with water, and as, when ink hasbeen applied to such portions, the wa ter and oil do not separate intodistinct bodies when heavy pressure is applied between the plate and thepaper or rubber blanket upon which the impression is to be lieve thiscondition explains why my plate will print with so greatly increased aspeed. This emulsification of the ink and water I regard as veryimportant and believe it to be a strong factor both in obtaining therelatively great density of color which the plate will print and thehigh speed with which it will print.

By the term mechanical inking, as used in the claims is meant inking bythe more use of a mechanically-operated roller or other device asdistinguished from rubbing, stipplingwith a brush, or rolling by hand,or other manual operation.

Bythe term chromic acid salt it is meant to include every compound ofchromium having the property of more or less hardening organic matterunder the action of light.

Many modifications of my invention can be made without departingtherefrom or from the scope of the claims, and my invention is notlimited to the particular embodiment chosen for the purpose ofillustration.

Haying particulary described my invention, what I claim and desire tosecure by Letters Patent is:

1. A printing plate comprising an unreticulated colloid film which iscapable of printing after mechanical inking.

2. A printing late comprising an unrej at llll

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tgttaatt ticulated gelatine film which is capable of printing at'termechanical inking.

3. A printing plate comprising a colloid film which is capable ofprinting after mechanical inking without the use of glycerin or othersimilar swelling means.

4:. A printing plate comprising a gelatine film while is capable ofprinting alter mechanical inking without the use of glycerin or othersimilar swellingmedium.

5. A printing plate comprising a colloid film having dots or grainsphotographed thereon which in the finished plate are unaltered from theform in which they were originally photographed on such plate.

ti. A printing plate comprising a gelatine film having dots or rainsphotographed thereon Which in the finished plate are un altered from theform in which they were originally photographed on such plate.

A printing plate comprising an unreticulated colloid film havingink-receptive portions that are interrupted by relatively very finedots, or grains, or similar devices.

8. A printing plate comprisin an unreticulated gelatine film havinginlrreceptive portions that are interrupted by relatively very finedots, or grains, or similar devices.

9. A printing plate comprising a colloid film having ink-receptiveportions that are interrupted by dots, grains or similar devices thatare photographed thereon.

10. A printing plate comprising a gelatine film having ink-receptiveportions that are interrupted by dots, grains or similar devices thatare photographedthereon.

ll. As an article of manufacture, a photogelatine printing plate havingthe ability to take on ink selectively as to its light aection from aninking roller passed over its surface at a rate exceeding six inches persecond.

12. A planographic printing plate capable of receiving ink selectivelyas to its light affection, from a roller passed over its sur- 1 face ata speed greater than six inches per till lltl

second, in which the portions of the plate unatlected by light arecomposed of a collo-id.

13. A planographic printing plate capable of receiving ink selectivelyas to its light affection, from a roller passed over its surface at aspeed greater than six inches per secend, which comprises a colloidfilm, all of the original colloidal material of 'the film being presentin the portions of the finished plate unafiected by light.

ll. A printing plate in which the ink-recaptive image is composed of anunreticulated colloid that is capable of accepting moisture.

15. A printing plate in which the ink-receptive image is composed of anunreticulated gelatinethat is capable of accepting moisture.

16. A planographic printing plate in which the ink-receptive image iscomposed of a colloid that is free from granular structure and capableof accepting moisture.

17'. A planographic printing plate" in which the ink-receptive image 1scomposed of a gelatine that is tree from granular structure and capableof accepting moisture.

18. A printing plate capable of printing after mechanical inking andcomprising an unreticulated colloidal film that in selectively receptiveto ink, all of the original colloidal material of the film being presentin the finished plate.

19. A printing plate capable of printing after mechanical inking andcomprising an unreticulated gelatine film that is selectively receptiveto ink, all of the original gelatinous material of the film beingpresent in the finished plate.

20. A printing plate capable of printing after mechanical inking andcomprising an unreticulated colloidal film having the image representedby a mere change in the water-receptivity of the corresponding portionsof said film.

21. A printing plate capable of printing after mechanical inking andcomprising an unreticulated gelatine film having the image representedby a mere change in the water-receptivity of the corresponding portionsof said film.

22. A printing'plate comprising a colloid film having the imagerepresented thereon by means of dots or grains formed in a camera.

23. A printing plate comprising an unreticulated colloid film having theimage rep resented thereon by means of dots or grains formed in acamera.

2 1. A printing plate capable of printing after mechanical inking andcomprising an unreticulated colloidal film having the image representedby a mere change in the water-receptivity of the corresponding portionsof said film and without the removal of any portions of the colloidalmaterial of the film.

25. A printing plate capable of printing after mechanical inking andcomprising an unreticulated gelatine film having the image representedby a mere change in the water receptivity ot the corresponding portionsof said film and without the removal of any portions of the gelatinousmaterial of the film.

26. A printing plate capable of printing atter mechanical inking andcomprising a colloid film, in which has been incor porated a chromicacid salt that has been exposed to light, and the hardness of thelightafiected portions of which has been increased by the application ofother hardening-means.

27. A printing plate capable of printing ill) after mechanical inkingand comprising a gelatine film, in which has been incorporated a chromicacid salt that has been ex osed to light, and the hardness of the ligt-afi'ected portions of whichhas been increased by the application ofother harden ing means. 1

28. A printing plate capableof printing.

after mechanical inking and comprising a colloid film consisting ofhardened and relatively unhardened portions, the hardened portionscomprising a chromic acid salt, and having been subjected to exposure tolight and further subjected to the action of a hardening agency, therelatively unhardened portions remaining relatively unaltered.

29. A printing plate capable of printing after mechanical inking andcomprising a gelatine film consisting of hardened and relativelyunhardened portions, the hardened portions comprising a chromic acidsalt, and having been subjected to exposure to light and furthersubjected to the action of a hardening agency, the relatively unhardenedportions remaining relatively unaltered.

30. A printing plate comprising a colloid film consisting of hardenedand relatively unhardened portions, the hardened portions comprising achromic acid salt and having been subjected to exposure to light andfurther subjected to the action of alcohol, the relatively unhardenedportions remaining relatively unaltered;

31. A printing plate comprising a gelatine film consisting of hardenedand relatively unhardened portions, the hardened portions comprising achromic acid salt and having been subjected to exposure to light andfurther subjected to the action of grain alcohol, the relativelyunhardened portions remaining relatively unaltered.

32. A printing plate comprising a colloid film consisting of hardenedand relatively unhardened portions, the hardened portions comprising achromic acid salt and having been subjected to exposure to light andfurther subjected to the action of grain alcohol and heating, therelatively unhardened portions remaining relatively unaltered.

A printing plate comprising a gelatine film consisting of hardened andrelatively unhardened portions. the hardened portions comprising achromic acid salt and having been sub ected to exposure to light andfurther subjected to the action of grain alcohol and heating. therelatively unhardened portions remain ng relatively unaltered.

film in which has been incorporated a chromic acid salt that has beenexposed to light and the hardness of the light-afiectcd portions ofwhich has been increased by the use of a hardening agent which, when theexcess thereof has been removed, leaves said light-affected portions ina dry state.

35. A printing plate comprising a colloid film in which has beenincorporated a chromic acid salt that has been exposed to light and thehardness of the light-affected portions of which has been increased bythe use of a hardening agent which, when the excess thereof has beenremoved, leaves the said film in a dry state.

36. A printing plate comprising a colloid film inwhich has beenincorporated a chromic acid salt that has been exposed to light, and thehardness of the light-affected portions of which has been increased bythe use of a hardening agent which is not absorbed by the film.

37. A printing plate comprising a colloid film in which has beenincorporated a chromic acid salt that has been exposed to light, and thehardness of the light-afl'ected portions of which has been increased bythe application of a hardening agent which is not absorbed by saidlight-aiiected portions.-

38. A printing plate comprising a colloid film in which the partscorresponding to the image are relatively highly receptive to ink whenwet with water.

39. A printing plate comprising a gelatine film in which the partscorresponding to the image are relatively highly receptive to ink whenwet with water.

40. A printing plate comprising an unreticulated colloid film in whichthe parts corresponding to the image are receptive to ink when wet withwater.

41. A printing plate comprising an unreticulated gelatine film in whichthe parts corresponding to the image are receptive to in-k' w'hen wetwith water.

42. A printing plate comprising a colloid film having parts.corresponding to an image that are receptive to ink, the other portionsof said film being capable of continuously repelling ink by the mereapplication of water.

' 43. A printing plate comprising a gelatine film havlng partscorresponding to an image that are receptive to ink, the other portionsof said film being capable of continuously repelling ink by the mereapplication of water.

44. The process of making a printing plate, comprising sensitizing acolloid film with a chromic acid salt, subjecting the same to theselective action of light to form an image, hardening the light-affectedareas more than the unaffected areas, and removing the unaffectedchromic acid salt. 34. A printing plate comprising a colloid 45. Theprocess of making a printing plate, comprising sensitizing a colloidfilm with a chromic acid salt, subjecting the same to the selectiveaction of light to form an image, and hardening the light-affectedneonate areas more than the unafiected areas without removing anyportion of the colloid. V

lb. The process of making a printing plate, comprising sensitizing acolloid film with a chromic acid salt, subjecting the same to theselective action. of light to form an image, hardening thelight-affected areas,

removing the unaffected chromic acid salt, and heating the plate.

47. The process of making a printing plate, comprising sensitizing acolloid film with achromic acid salt, subjecting the same to theselective action of light to form an image, hardening the light-affectedareas without removing any portion of the colloid, and heating theplate.

A8. The process of making a printing plate comp-rising sensitizing agelatine film with a chromic acid salt, subjecting the same to theselective act-ion of light'to form an image, hardening thelight-affected areas more than the unaffected areas, and removing theunafiected chromic acid salt.

A9. The process of making a printing plate comprising sensitizing agelatine film with a chromic acid salt, subjecting the same to theselective action of light to form an image, and further hardening thelight affected areas more than the unall'ected areas without removingany portion of the gelatine. c

50. The process of making a printing plate comprising sensitizing agelatine film with a chromic acid salt, subjecting the same to theselective action of light to form an image, further hardening thelight-ail'ected areas, removing the unafii'ected chromic acid salt, andheating the plate.

51. The process of making a printing plate comprising sensitizing agelatine film with a chromic acid salt, subjecting the same to theselective action of light to form an image, 'lurther hardening thelightaffected areas without removin any portion of the gelatine, andheating the plate.

52. The process or makin a printing plate comprising forming a. colloidfilm on the plate and sensitizing the film with a chromic acid salt byapplying thereto a solution of said salt, exposing said film to a lightimage and hardening said film.

53. The process of making a printing plate comprising forming on abacking a colloid film that is sensitized by a chromic acid salt anddrying said film by a temperature that is not greater than 130 F,exposing said film to a light image and hardening said film.

5d. The process of making a. printing plate comprising forming agelat-ine film on the plate and sensitizing the film with a chromic acidsalt by applying thereto a solution of said salt, exposing said film toa light image and hardening said film.

55. The process of making a printing plate that is' not greater than 130comprising lormin on a backing a gelatine film rendered sensitive by achromic acid salt and drying said film by a temperature F, exposing saidfilm to a light image and hardening said film.

56. As a composition of matter, a colloid in which has been incorporateda chromic acid salt, which has been hardened by the action of light, andthe hardness of which has been increased by immersion in grain alcohol.

57. As a composition of matter, a colloid,

in which has been incorporated a chromic acid salt, which has beenhardened by the 59. As a composition of matter, a colloid,

in which has been incorporated a chromic acid salt and which has beenhardened by light, and the hardness of which has been further increasedby the application of grain alcohol as a hardening agent.

- 60. As a composition of matter, a gelatine in which has beenincorporated a chromic acid salt, which has been hardened by the actionor light, and the hardness of which has been increased/by immersion ingrain alcohol.

61. As a compositlon of matter, a gelatine in which has beenincorporated a chromic,

acid salt, which has been hardened by the action of light, and thehardness of which has been increased by immersion in grain alcohol andby heating.

62. As a composition of matter, a, gelatine, in which has beenincorporated a chromic acid saltand which has been harddened by light,and the hardness oil which has been further increased by the applicationof a hardening agent.

63. As a composition of matter, a gelatine, in which has beenincorporated a chromic acid salt, and which has been hardened by lightand the hardness of which has been further increased by the applicationof a grain alcohol as hardening agent.

64. As a composition of mattena colloid, in which has been'incorporateda chromic acid salt some only of which has been hardened by light, andthe hardness of which has been further increased by heating both thehardened and unhardened portions of said colloid being present in saidcomposition.

65. As a composition of matter, a gela- .tine,- in which has beenincorporated av been hardened by light, and the hardnessof which hasbeen further increased by heating both the hardened and unhard'enedporplication of a hardening agent and by heating it.

68. In the process of forming a printing plate having a colloid film,the step which comprises hardening the film with formaldehyde beforesensitizing it. v

69. In the process of forming a printin plate having a colloid film, thestep 0 hardening the film before sensitizing it.

70. In the process of forming a printing plate having a gelatine film,the step of hardening the film before sensitizing it.

71. In the process of forming a printing plate having a colloid film,thestep which comprises hardening the film with grain alcohol andformaldehyde before sensitizing it. V

72. In the process of forming a printin plate having a gelatine film,the step which comprises hardening the film with grain alcohol andformaldehyde before sensitiz- 73. The process of making a printing platecomprising coating a backing with gelatine, hardemng the gelatine withformaldehyde, sensitizing the gelatine with a chromic acid salt,hardening the light-affected areas by the use of means which will notequally harden the unaffected areas, and

. then removing the unaffected chromic acid salt from the plate.

74. The process of making a printing platecomprising coating abackingwith colloid, hardening the'colloid with formaldehyde, sensitizing -thecolloid with a chromic acid salt, hardening the light-affected areas bythe use of means which will not equally harden the unaffected areas,'and

then removing the unaffected chromic acid salt from the plate. r

75. The process of makin a printing plate comprising coating a backingwith gelatine, hardening the gelatine with formal: dehyde, sensitizingthe gelatine with a chromic acid salt, applying a light-restrainingagent thereto, hardening the light-affected areas by the use of meanswhich will not equally harden the unaffected areas-and thenremoving theunaffected chromic acid salt from the plate.

76. The process of making a printing plate comprising coating a backingwith a colloid, hardening the colloid with formaldehyde, sensitizing thecolloid with a chromic acid salt, applying a light-restraining agentthereto, hardening the light-affected areas by the use of means whichwill not equally harden the unaffected areas and then removing thunaffected chromic acid salt from the plate.

77. The process of making a printin plate comprising coating a backingwitfi gelatine, hardening the gelatine with formaldehyde, sensitizingthe gelatine with chromic acid salt, hardening the light-ab 'fectedareas by the use of means which will not equall harden the unaffectedareas, removing t e unaffected chromic acid salt from the plate and thenheating said plate.

78. The process of making a printing plate comprising coating a backingwith a colloid, hardening the colloid with formaldehyde, sensitizing thecolloid with a chromic acid salt, hardening the light-affected areas bythe use of means which will not equally harden the unaffected areas, re-

moving. the unaffected chromic acid salt from the plate and then heatingsaid plate.

79. The process of makin aprinting plate comprising coating a backingwith gelatine. hardening the gelatine with formaldehyde. sensitizing thegelatine with a chromic acid salt, applying a light-restraining agentthereto, hardening the light-affected areas by the use of means whichwill not equally harden the unaffected areas, removing the unaffectedchromic acid salt from the plate, and then heating said plate.

80. In the process of forming a printing plate having a colloid film,the step which comprises increasing the difference in waterreceptivity'between those portions of the plate which are more receptlve to waterthan those which are less so.

81. In the process offorming a printing plate having a colloid film, thestep which comprises increasing with grain alcohol the difference inwater-receptivity between those portions of the plate which are morereceptive to water thanthose which are less so.

82. The process of printing which comprises the application of ink to awet unreticulated colloidal surface and the printing or transfer of saidink.

83. The process of printing which comprises giving to portions of anunreticulated colloidal surface the capacity when wet to receive ink toform an image, and to other portions of said surface the capacity torepel ink. applying ink to said surface and printing therefrom.

84. The process of printing Which comlll ' All till iataata prises theapplication of ink to a wet unreticulated colloidal surface, thetransfer of said ink to a rubber blanket, and the trans fer of said inkimage from said rubber blanket to its final support.

85. The process of printing which com- I prises forming on a backing acolloid coating, sensitizing said colloid with a chromic acid salt,exposing said colloid to a light image, accentuating the difierence inwaterreceptiveness between the exposed and unexposed portions of thecolloid, moistening said plate and applying ink thereto.

86. The process of printing which comprises forming on a backing acolloid coating, sensitizing said colloid with a chromicacid salt,exposing said colloid to a light image, accentuating the difference inwaterreceptiveness between the exposed and unexposed portions of thecolloid by hardening said exposed portions, moistening said plate andapplying ink thereto.

87. The process of printing which comprises forming on a backing agelatine coating sensitizing said gelatine with a chromicacld salt,exposing said gelatine to a light image, accentuating the difi'erence inwaterreceptiveness between the exposed and unexposed port-ions of thegelatine by hardening said exposed portions, moistening said plate andapplying greasy ink to the less water-receptive areas.

88. The process of printing which c0mprises formlng on a backing agelatine coating, sensitizing said gelatine with a chromic acid salt,exposing said gelatine to a light image, accentuating the difierence inwaterreceptiveness between the exposed and unexposed portions of thegelatine, moistening said plate and applying ink thereto.

89. The process of printing which comprises forrning on a backing agelatine coating, sensitizing said gelatine with a chromic acid salt,exposing said gelatine to a light image, accentuating the difierence inwaterreceptiveness between the exposed and unexposed portions of theg'elatine, moistcning said plate and applying ink thereto.

90. The process of printing comprising forming a plate having a colloidfilm, renvdering said film selectively water receptive according to theimage desired, applying only a single ink-repelling medium to said plateand then applying ink to said plate.

91. The process of printing comprising forming a plate having a colloidfilm, rendering said film selectively watcr-receptive according to theimage desired, applying only water to saidplate and then applying ink tosaid plate.

92. The process of printing which comprises applying ink to a wetsurface, emulsifying said ink with water from said wet surface, andprinting said ink.

93. The process of printing which com.- prises applying ink to a wetcolloid surface, emulsifying said ink with water from said wet colloidsurface, and printing said ink.

94. The process of printing which cornprises applying ink. to a wetgelatine surface, emulsifying said inkwith water from said wet surface,and printing said ink.

95. The process of printing which comprises applying ink to a wetsurface, emulsifying said ink with water from said wet surface,depositing saidemulsified ink upon a rubber blanket, and redepositingsaid emulslfiedink upon the print or final support.

96. The process of printing which comprises applying ink to a wetcolloid surface, emulsifying said ink with water from said wet surface,depositing said emulsified ink upon a rubber blanket, and redepositingsaid emulsified ink upon the print or final support. I

97. The process of printing which comprises applying ink to a wetgelatine surface, emulsifying said ink with water from said wet gelatinesurface, depositing said emulsified ink upon a rubber blanket, andredepositing said emulsified ink upon the print or final support. 7

98. The process of printing which cornprises the steps of applying inkto an unretit-ulated colloidal planographic plate, the image on whichhas been formed by the action of light and which has remained melitchanically unmodified between the step of exposure to light and the saidstep of applying the ink, and impressing said ink upon a support.

99. The process of making a printing plate comprising forming on abacking a colloid coating, rendered sensitive with a chromic acid salt,exposing the same to a light image, hardening the light-affected areasby means which will not equally harden the unaffected areas, removingthe unaffected chromic acid salt from the plate, and heating the plate,and during which process avoiding heating the plate to 130 F. whileunaltered chromic acid salt is present in the colloid coating.

100. The process of making a printing plate comprising forming on abacking a gelatine coating rendered sensitive with a chromic acid salt,exposingthe same to a light image, hardening the light-effected areas bymeans which will not equally harden the unaffected areas. removing theunaffected chromic acid salt from the plate, and heating the plate, andduring such process avoiding heating the plate to F. while unalteredchromic said gelatine to a light image, then without removing theunaltered portion of said salt, accentuating the difference inwater-receptiveness between the exposed and unxposed portions of thegelatine, removingthe unafected portions of said salt from the saidlatin'e coating hardening said gelatine coatmg and heating said plate,moistening said plate, applying ink thereto, emulsifying said ink withthe said water on said plate and transferring said ink. s

102. The process of printing which comprises forming on a backing acolloid coat 1n hardening said coating, sensitizing'said co loid with achromic acid salt, exposing said colloid to a light image, then withoutremoving the unaltered portion of said salt, accentuating the differencein water-receptiveness between the exposed and unexposed portions of thecolloid, removing the unaffected portions of said salt from the saidcolloid coating, hardening said colloid coating and heating said plate,moistening said plate, applying ink thereto, emulsifying saidROBERT-JOHN.

